Many vehicles now utilize hybrid-electric powertrains in order to increase the efficiency of the vehicle. Hybrid-electric powertrains typically improve overall vehicle fuel efficiency by supplementing an internal combustion engine with electric motors, such that less power output is required of the internal combustion engine, as power from the electric motors may also be utilized in situations when maximum powertrain output is required, such as acceleration, or climbing a grade. Additionally, hybrid-electric powertrains may be utilized to power equipment mounted to a vehicle, such as, for example, a lift, an auger, a post hole digger, a crane, or other known equipment that may be utilized when a vehicle is not in motion. Such power equipment may be powered through a power take off (“PTO”) that may be driven by electric motors of the hybrid-electric powertrain to reduce the time an internal combustion engine is operated. For instance, if torque required to operate the equipment mounted to the vehicle is generally low, or the equipment is only used intermittently, it is contemplated that only the electric motors may be utilized. However, if the torque demand of the equipment is high, or the equipment is used for a prolonged period, the internal combustion engine may be used in place of, or in addition to, the electric motors to power the equipment.
If the hybrid-electric powertrain is providing power to the PTO from electric motors, and conditions are such that power is also required from the internal combustion engine, a source of torque to power a starter of the internal combustion engine is required. The source of torque to start the internal combustion engine provides issues not experienced in conventional vehicles, as a battery would simply provide electrical power to a starter motor that was utilized to start the internal combustion engine. However, in many hybrid-electric powertrains, an electric motor and generator is used to power the starter, or to simply turn the crankshaft of the internal combustion engine. However, if a battery pack powering the electric motor and generator does not have sufficient charge, the internal combustion engine may not be stared. Another situation that may prevent the electric motor and generator from providing torque to start the internal combustion engine is when the electric motor and generator is providing continuous power to the equipment mounted to the vehicle. In such a situation, the electric motor and generator may not have sufficient torque to both power the equipment and start the engine, thus, the torque to the equipment would be reduced while the engine is being started. This may result in unacceptable performance, as the equipment may have to temporarily turn off.
Therefore, a need exists for a system that provides an alternative source to provide torque to start an internal combustion engine, and method of determining when the alternative source to provide torque should be utilized.